Displaying 2 results from an estimated 2 matches for "pderiv".
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2007 Nov 07
3
Can I replace NA by 0 (if yes, how) ?
...trying to fit some points with a 8-degrees polynom (result of lm is
stored in pfit).
In most of the case, it is ok but for some others, some coefficients are
"NA".
I don't really understand the meaning of these "NA".
And the problem is that I can't perform a derivation
(pderiv<-as.function((deriv(polynomial(pfit$coefficients))))) on pfit due to
the presence of these "NA".
I tried the functions na.omit and na.exclude but "NA" are still there.
I tried to replace manually "NA" by 0. The fit seems ok and then I can
derive the polynom.
But c...
2007 Nov 06
1
How to find the zero (only the real solution) with the package polynom ?
Hello,
I have 3 columns : a, b and a*b
I would like to find the pair (a,b) so that a*b is the minimum but not from
the points I measured but from the fit of the curve (I have more points that
the ones given below but I fit only on this part because I
know that the minimum a*b is in this interval).
I thought doing it this way :
- to fit a*b=f(a)
abfit<-lm(ab ~ poly(a,8,raw=T))
- to use the